This invention relates, in general, to methods of fabricating semiconductor devices, and more particularly, to methods for etching semiconductor substrates.
There has been an ongoing effort to produce semiconductor devices with improved performance and functionality. In some cases, the improvement in performance is achieved by developing sophisticated semiconductor device structures, which is accomplished with a complex processing sequence. Traditionally, all semiconductor devices have been formed on only one side of a semiconductor substrate. However, many sophisticated semiconductor structures now require that processing occur on both sides of the semiconductor substrate.
A manufacturing flow which processes both sides of a semiconductor substrate requires that the process steps occurring on one side be accurately aligned to the process steps occurring on the opposite side. Up to now, this alignment has been provided by aligning the flat or flats of a semiconductor substrate to a known orientation. This traditional method, however, is not sufficient for aligning a semiconductor substrate on wafers with large diameters when sub-micron device structures are fabricated by processing both sides of the semiconductor substrate.
Accordingly, it should be appreciated that it would be advantageous to provide a method of forming structures in a semiconductor substrate such that the structures can be used to accurately align the substrate. It would also be advantageous if the method could be used to form other semiconductor device structures.